The following account of the prior art relates to one of the areas of application of the present invention, the positioning of a programming device for a hearing aid relative the hearing aid.
There may be problems with positioning a wireless programming unit correctly relative to a hearing aid to be programmed (‘programming’ e.g. comprising acts of customizing or adapting the hearing aid to a specific wearer's needs, e.g. by forwarding parameters for signal processing algorithms, audiometric data of the wearer, etc.). The programming unit typically needs to be aligned properly according to the device it is programming (due to antenna constraints). Furthermore the unit will only function within a certain range of distances (due to power level constraints).
U.S. Pat. No. 5,343,295 deals with a positioning system using the intersection point between two laser beams to position an electrically powered vehicle relative to an electric power station. Uses laser diodes with equal size beam-spots (and substantially collimated (non-focussed) beams).
WO 2005/098475 describes a sensing device for determining the position and orientation of an object based on geometrical relationships between light sources on the object and their images on the sensing device (including intensities or magnitudes).